“A Flow Dynamic Rationale for Accelerated Vascularized Composite Allotransplant Rejection”

Background: From 1996 to 2000 Diefenbeck et al. carried out 6 knee vascularized composite allotransplants(VCA). The VCAs were composed of bone, soft tissue, and the femoral vascular pedicle (25-40 cm total length). All rejected between 14 to 56 months. The failures were attributed to chronic rejection (CR). In 2008 the Louisville team lost their fourth patient's hand transplant at 8 months. During the rejection workup the senior surgeon's intra-operative findings noted a thickened arterial pedicle attributed to intimal hyperplasia (IH) with significant fibrotic perivascular tissue and a near "no flow phenomenon". No cutaneous rejection was appreciated and failure was attributed to CR. Methods: Data was collected from two teams, one in Germany and the other in Louisville. The population under study was the six knee and one hand VCA. The factor of interest was the long donor arterial pedicle. The outcome measurements were the VCA survival time and histopathological results. Results: There are only seven published VCA cases where a donor artery >25cm was used. This cohort represents a 100% accelerated failure rate. The etiology of these VCA losses remains unexplained. The donor arteries suffered from TCMR and ischemia induced media/adventitial necrosis. Conclusion: We hypothesize the donor artery rejected at an accelerated rate due to ischemia caused by disruption of the external vasa vasorum in conjunction with TCMR induced IH which lead to disruption of the Windkessel Effect. The loss of this Effect presented as IH accelerated by ischemia causing an expedited VCA failure. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Financial Disclosure Statement: None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this manuscript. No funding was received for this article. Presented at (if applicable): Not Applicable to this manuscript. Corresponding author: Warren C. Breidenbach, MD, MS, 300 Convent Street, Suite 1330, San Antonio, TX, USA 78205, warrenbreidenbach@gmail.com ©2019American Society of Plastic Surgeons

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